<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    /*id选择器*/
    #p1{color: red}
    /*类选择器*/
    .c1{color: purple}
    /*分组选择器,将多个选择器合并成一个选择器*/
    #p1,.c1{
      background-color: pink;
    }
    /*属性选择器*/
    input[type='text']{background-color: red}
    /*任意元素选择器*/
    *{
      border: 1px solid blue;/*边框:粗细 实线 颜色*/
    }
  </style>
</head>
<body>
<input type="text">
<input type="password">
<p id="p1">苹果</p>
<p>香蕉</p>
<p class="c1">橘子</p>
<h3>冰箱</h3>
<h3>洗衣机</h3>
<h3 class="c1">电视</h3>
</body>
</html>